Spot-welding apparatus



Mlch 17, 1931. T, M HUNTER SPOT WELDING APPARATUS Filed June 21, '1929 2 Sheets-Sheet l vwewtoz THOMAS M. HUNTER 351g 5C@ @Mme/13 March 17, 1931. T. M. HUNTER SPOT WELDING APPARATUS Filed June 2l. 1929 2 Sheets-Sheet 2 m. @Pi

gnou/tbox v THOMAS M. HUNTER 3&4, @www `Patented Mar. 17, 1931 y I UNITED 'STATES PATENT oFFicE THOMAS M. HUNTER, F4 EAST ORANGE, NEW JERSEY, ASSIGNOR TO AMERICAN TRANSFORMER^ COMPANY, NEWARK, NEW JERSEY sPo'r-wELDING APPARATUS Application led June 21, 1929. Serial No. 372,633.

This invention relates to a unitary piece of Referring now to the drawings, wherein apparatus which is particularly adapted for like numbers refer to corresponding parts in use in the spot Welding of small parts, espethe various views, 1 generally refers to a cially those used in the construction of vacframework carrying the various parts of the 5 uum tubes used in radio receiving sets; but apparatus. On a flange 2 of the frame l, is 5;,

of course, the apparatus may be used for mounted an alternating current transformer other purposes, 'L 3 having a primary P, and a relatively heavy One of the objects of my inventionis to current secondary S with taps 4 of bar conprovide a spot welding apparatus in which ductors welded or soldered to the convoluall of the parts are brought together into a tions 0f the Secondary S. The method of 60 single, compact, unitary piece of apparatus constructing the transformer, is along the which is readily portable for the convenience lines disclosed in my Patent 1,547,497, is-

of the operator. Sued July 28, 1925.

l,Another object of my invention is to pro- Mounted on the back of the framework, is

vide a spot welding apparatus which by reaa rheostat 5 which is connected as shown in e@ son of its compactness is highly efficient, due Flgure 7, to the primary circuit of the transtotthe low electrical losses brought about by former, WhlChv Primary S adapted t0 be 00nths Particular design, nected to any suitable source of current hav- Another object of my invention is to proing 110 or 220 volts, etc. Mounted closely vide an apparatus such. as described, wherein adjacent the rheostat 5 on the back of the 70 l the parts are so arranged as to protect the framework, are tW0 COIIC members 6 and operator from flashes which occur when 7 which are connected to the primary circuit one or more parts the circuits included' 0f the transformer and 3S IldCled,J these within the apparatus are Opened at the beswitch contacts 6 and 7 are normally open.

ginning or end of the Welding operation. Projecting forwardly from the frame are 75 Another object of my invention is to'protW0 lllgS 8 and 9 between which is supported Vide a 'Spot apparatus having gen- Shaft; )I SPlIldle 10. l The Spindle 10 lS lleld erally a strong and rigid construction, and 1n POSltlOIl 1n D Vfitlsfctoly manner 21S by one in which the moving parts are positive Set SCIeW 11. 1L )ivotally mounted on the 3;, in their Operation spindle 10, 1s an irregularly shaped lever 12 so These and @hel-.Objects will be @1emto one lwhich is normally held in the position shown skilled in this art, after reading the speci- 111 Flgllres 1 and 2 by a spring 13 having one y cation taken in connection with the annexed @11d attached t0 the' I'mB'L and the Other drawings7 wherein; end'to a pin 14, fastened to the lever 12. 3:. Figure 1 is a front View of the spot Weld- In ordei` to give a substantial bearing, the sa in apparatus. lever l2 is provided with an integral hub iguro 2 is a side elevation looking from 15. Attilched t0 the level' 12 Onll'le Side Opthe right of Figure 1, but with the cover poslte the hub 15, in any satisfactory manner Shown in dotted position, as by screw 16 and dowel pin 17, is a mem- 40 Figure 3 is a View. 0f the rear part of the ber 18 having a lip 19 which acts as a cam. 90 apparatus with the @over removed, v y Preferably the hOle lll the member 18 fOI lille Figure 4 is a part-sectionalview on the screw 16, is made somewhat larger than the line i--if of Figure 1. diameter of the screw, whereby the cam mem- Figure 5 is a view 0n the same line, but ber 18 may be oscillatedslightly about thel looking in the direction of the arrows 5--5. dowel 17 in order to get a correct adjustment 95 Figure 6 is a 'part-sectional view on the 0f the cam 19, which is adapted to engage a line 6 6 of Figure 1,With certain of the parts pin 20 carried on a lever 21. The lever 21 in diiferent position of operation. is preferably provided with an insulated Figure 7 is a diagrammatic view of the busliin'gv22 which is adapted to engage the 7 circuit of the apparatus. contact member 7 to force it into engagement 100 with the contact member 6, as will be more fully described later. The lever 21 is held in the position shown in Figure 4, by a spring 23.

To the lever 12, is fastened a stud 24 having an extension in the shape of a pin 25 which is preferably threaded on the outer end to receive an adjusting nut 26. Positioned over the pin 25, is a spring 27, one end of which rests against a stud 28 through which the pin 25 passes. The stud 28 projects through a welding contact arm 29, and the projecting end 30 acts as a stop for an adjusting screw 31 carried by a bracket 32 which is mounted on the frame 1. Thelever 12 has a projecting part or arm 33, to which is attached a suitable operating member, such as a chain 34, which is preferably brought out and arranged so that tension may be applied to the chain by means of the operators foot, whereby the lever 12 is operated.

The welding arm 29 is pivotally supported on a stub shaft 35 carried on the support member 36,'f0rming part of frame 1. The electrode arm 29 is preferably made of cast copper of considerable cross-sectional area, so as to carry a relatively heavy current out to the electrode 37, which is preferably of copper and pointed at 38 to the desired shape. The electrode 37 is preferably adjustable in the arm 29 by means of a set screw 39, it being understood that the end of the arm 29 is split at 40 to provide for this adjustment.

Cooperating with the movable arm electrode 29, is a stationary electrode arm 41 carrying an electrode 42, having its end shaped at 52 to cooperate with the end 38. rllhe electrode 42 is preferably adjustable by means of a set screw 43, the arm 41 being slotted at 44 to provide for this adjustment. rllhe arms 29 and 41 are insulated one from the other,

and in order to do this, it is preferable to insulate/the arm 41, which is mounted on frame 1, through the medium of screws 45 and insulators 4G. One end of the secondary S of the transformer connected by means of a relatively heavyconductor 47, preferably made of a plurality of thin copper strips, to the electrode arm 41 by means of a cap screw 48.

Attached to the arm 29, through the me-` dium of a terminal 49, is a flexible conductor 50, which is connected to the opposite working terminal of the secondary S of the transformer. As will be seen by reference to Figure 3, the conductors 47 and 50 maybe shifted to any one of the taps 4, holes 51 being provided in these taps for making these connections which are very short and of high conducting material, such as copper, whereby the voltage drop in them is substantially nil, it being understood that the transformer secondary S is of a relatively low voltage, on the order of one to four r volts, and the current for this spot welding apparatus is in the neighborhood of one to two hundred amperes.

Coming now to the operation of my apparatus, keeping in mind that the source ot' current is connected to the apparatus with the leads 53, vthe work to bevspot welded is placed between the Contact points 38 and 52, and the operator then applies force or power to the chain 34. This starts the lever 12 into operation, and during the first' part of the movement of the lever 12, the welding contact points 38 and 52 are brought into engagement with the work through the medium of thestud 24 acting on the stud 28, which is fastened to the movable welding arm 29.

Immediately after these contacts 38 and 52 are closed on the work, the cam 19 engages the pin 20 "(see Fig. 4) causing the pin to ride over the outer surface of the cam 19, thereby pushing the lever 21 against the switch Contact 7, moving it into engagement with the switch contact 6, thereby closing the primary circuit of the transformer and` causing current to flow in the secondary through the spot welding contacts 38 and 52. Continued movement of the lever 12 to the position shown in Figure 6, is permitted by reason of the spring 27, which vallows the pin 25, forming a continuation of the stud 24. tobe drawn downward against the spring 27. rl`he spring 27 also regulates the amount of pressure applied tothe welding contacts. As the lever 12 is moved to the end of its stroke, the pin 20 slips off the end 54 of the cam 19, allowing the lever 21 to be returned by the spring 23 to its normal position, as shown in Figure 4, thereby opening they primary circuit of the transformer and stopping the welding operation.

The operator then releases the strain on the chain 34, and the -spring 13 returns the lever 12 back to its normal position as shown in .Figure 4, thereby1also moving the arni 29 to taps, one of which is shown at 55, l prefer to lou use the rheostat 5 in the primary of the transformer, in order t get a very close regulation of the current delivered from the secondary. However, in some cases, the rheostat 5 may not be necessary, but when it is used, I mount it on the back of a part of the framework and operate it by any suitable means, as by a knob 56. y

1t will be observed that the switch members 6 and 7 are concealed from the operator so that the operator will get no Hash when the switch contacts are open` as described, and by breaking the primary circuit previous to the opening of the contacts at the welding electrodes, no arc or Hash is produced bel so as to conceal the transformer, the rheostat,

and the ,switch members, and protect them ,L from dust and dirt and injury.

-secondary of a wel It will be clearly apparent that while I have illustrated in the drawings, on're'duced scale, a preferred form of my invention, various changes may be made in the details, without departing from the spirit of my invention or the scope of the appended claims.

Having thus described my invention, what I claim is:

l. In a spot welding apparatus, a frame, a stationary welding contact arm fastened to the frame, a contact carried by said arm, a movable Welding arm carried byf the frame and carrying a contact to coo eratewith the rst contact, one of said arms eing insulated from the other and each being provided with means for attachin ay connection fromthe ding transformer, a pair of switch contacts mounted on the frame for closing and opening the primary circuit of said transformer, a rheostat for controlling the current in the primary of said transformer and carried by the frame, alever pivotally mounted on the frame, a cam carried l by the lever, a second lever positioned to actuate said switch contacts, a in carried by the second lever to be engage by said cam for the purpose described, an arm onthe ,first lever having a yielding connection with the movable welding arm, means for actuating said first lever, and mean-s for returning it to normal position after having been actuated.

2. In a spot welding apparatus, a frame, a stationary welding contact arm fastened to the frame, a contact carried by said arm, a

movable Welding arm carriedv by the frame and carrying a lcontact to cooperate with the first contact, one of said arms being insulated from the other and each being provided with means forattachin a connection from the secondary' of a wel ng transformer, a pair of switch contacts mounted on the fram@ for closing and opening the primary circuit of said transformer, a rheostat for controlling theO current in the primary of said transformer and carried by the frame, apair of levers mounted on the frame, one lever being provided with means for operation by an operator, and the second operated by the.y first, operating means between the two levers disposed so the first lever has a predetermined movement before movement of the second lever is started, an arm on the first lever' having a yielding connection with the movable Welding arm allowing the first lever to continue movement after closing said welding contacts on they Work, said second lever being actuated to close said switch contacts after the Welding contacts have been closed on the work, the operating means between the two levers being such as to permit the return of the second lever just before the first lever reaches its full stroke, whereby the primary circuit lis opened at said switch contacts before the welding circuit is opened oward the end of the return stroke of said ever.

3. In a spot welding apparatus, a frame, a

stationary welding contact arm fastened to the frame,a contact carried. by said arm, a movable welding arm adjustably carried by the frame and carrying a contact to cooperate with the first contact, one of said' arms being insulated from the other and each being provided with means for attaching al conl nection from the secondary of a welding transformer, a pair 'of switch contacts for closing and opening the primary circuit of a welding transformer, said switch contacts being mounted in concealed position from the operator lof the apparatus, means for regulating the current in the primary of the transformer, said means having an loperating member on the exterior of the frame, a pair of levers mounted on the frame, one lever being provided with means for operation by an operator, and the second operated by the first, operating means between the two levers disposed so the first lever has a predetermined .movement before movement of the second fore the welding circuit is o cned toward the end of the return stroke o said lever.

4.' A spot welding apparatus including a frame, a transformer fastened to the frame,

said transforn'ler having a primary and a` low voltage heavy current secondary, a stai tlonary weldlng contact arm fastened to the frame, a contact carried by said arm, a mov-v able welding arm carried by the frame and carrying a contact to cooperate with the first contact, one of said arms being insulated from the other and each being provided with lmeans for attaching a connection from thee secondary of said transformer, anpair of switch contacts mounted within the confines of the frame, said switch contacts being in the prlmary circuit of the transformer,

means for regulating the circuit in the-fprimary of the transformer, an operator-controlled lever pivotally mounted on the frame and carrying a cam, a second lever positioned to actuate said switch contacts, said second lever having a part engaged by said cam on the working stroke of the first lever tacts,

vlever part, allowing thesame to return to normal position to open tlie primary circuit of the transformer before the first lever is returned to open the welding circuit, and means to insure that the firstalever is returned to normal position on release by the operator.

5. A spot welding apparatus including a frame, a transformer fastened to the frame, switch contacts mounted on the frame and connected in the primary circuit, a rheostat mounted on the frame but having an operating member extending through the frame, a cover for concealing the transformer, switch contacts and rheostat, a pair of welding conwelding arms for carrying said welding cont-acts mounted on the front of said frame, at least one of said arms being movable with respect to the-other, and one insulated from the other, said arms being connected to opposite parts of the secondary of the transformer by shortwihe'avy leads, an opera-l v tor-actuated lever having a yielding conneci from the other and each being provided with,`

tion to said movable welding arm, a second lever positioned to actuate said switch eontacts, cooperating means carried by both of said levers to actuate the second lever-to close said switch contacts after the yrst lever has been moved to close the welding contacts on the work, 'said means also co-acting to allow the second lever to return to normal position, thereby opening the primary circuit of the transformer before the first lever has reached the limit of its working stroke, and therefore before the welding circuit is opened, and means to insure that the first lever is returned to normal position to thereby open the welding circuit.

6. Ina spot welding apparatus, a frame, av

stationary welding contact arm fastened to the frameya contact carried by said arm, a movable welding arm carried by the frame and carrying a contact to cooperate with the first contact, one of said arms being insulated meansfor attaching a connection from the secondary of a welding transformer, a pair of switclrcontacts' in the primary circuit of the transformer, a cover for concealing the transformer and switch contacts, a pair of Welding arms carrying contacts, at least one of which contacts is adjustable in the arms, said arms being mounted on the'frame, and one of them being adjustable and movable with respectto the other, and one beinginsulated from the other, said arms being con- Iiected by short heavy conductors to oppositev parts of the secondary of said transformer,` an operator-actuated lever having a yielding connection to said movable welding arm, a second lever positioned to actuate said switch contacts, cooperating means carried by both of said levers to actuate the second lever to close said switch contacts after the first lever has been moved to close the welding contacts on the work, said means also co-acting to allow the second lever to return to normal position, thereby opening the primary circuit of' the transformer before the first lever has reached the limit of its working stroke, and therefore before the welding circuit is opened, and means to insure that the first leverl is returned to normal position to thereby open the welding circuiti 7. A spot welding apparatus including a frame, a pair of welding arms carrying con-l tacts, said arms being mounted on the frame, and at least one of them being adjustable and movable with respect tothe other, and one being insulated from the other, said arms having connections leading to the secondary of a transformer, switch contacts for opening and closing the primary circuit of the transformer, an operator-actuated lever having a yielding connection to said movable welding arm, a second lever positioned to actuate said switch contacts, cooperating means carried by both of said levers to actuate the second lever to closeisaid switch contacts after the first lever has been moved to close the welding contacts on the work, said means also co-acting to allow the second lever to return to normal position, thereby opening the primary circuit of the transformer before the first lever has reached the limit of its working stroke, and therefore before the welding circuit is opened, and means to insure that the first lever is returned to normal position to thereby open the welding circuit.

8. A spot welding apparatus including a frame, a pair of Welding arms carrying contacts, said arms being mounted on the frame, and at least one of them being adjustable andt movable with respect to the other, and one being insulated from the other, said arms-having connections leading tothe secondary of aul a transformer, switch contacts for opening and closing the primary circuit of the transformer, a rheostat also in the primary circuity of the transformer, a cover for concealing said switch contacts and rheostat, said weld-v ing contact arms extending from the front of the frame, whereby work may be quickly passed between said contacts, an operator-actuated lever having a yielding connection to said movable welding arm, a second lever po, sitioned to actuate said switch contacts,rooperati-ng means carried by both of said lcvers to actuate the second lever to close said switch contacts after the first lever has been moyed to close the welding contacts on the lto actuate said switch contacts,

work, said means also co-acting to allow the second lever to return to normal position, thereby opening the primarycircuit of the transformer before the first lever has reached the limit of its working stroke, and therefore before the welding circuit is opened, and means to insure that the first lever is returned to normal position to thereby open the welding circuit.

9. A unitary piece of welding apparatus including, a frame, aI transformer fastened to the frame, switch contacts and a rheosptat in the primary circuit of the transformer, a cover for concealing the transformer, switch contacts, and rheostat, welding electrodes mounted on the front of the frame and connected by short heavy conductors to the secondary of the transformer, at least one'of said electrodes being movable, and one being insulated with respect to the other,`an operating lever for the movable electrode and having a yielding connection therewith to allow the lever to be moved aftervclosing the electrodes on the work, a second lever positioned cooperating means carried by both of said levers to actuate the second lever to close said switch contacts after the first lever has been moved to close the welding contacts on the work, said means also co-acting to allow the second lever l to return to normal position, thereby opening the primary circuit of the transformer be- .fore the first lever has reached the limit of its working stroke, and therefore before the welding circuit is opened, and means to insure that the first lever is returned to normal position to thereby open the welding circuit.

10. A unitary piece of welding apparatus including; a frame, switch contacts and secondary welding electrodes all carried on the frame, a lever for rst closingsaid electrodes and then closing the primary-circuit, said lever carrying devices which will allow the primary circuit to open before the secondary circuit is opened at the electrodes on release 11. A unitary including; a frame,

a transformer, switch contacts 1n the primary circuit of the transformer, and secondary welding electrodes, all

carried on'the frame, a cover for concealing all but the electrodes, a pair of levers-co-acti ing' to first close said electrodes on to thework, and then close the primary circuit through said switch contacts, said levers acting on their return movements to first open the primary circuit' at said switch contacts,

and `then open the secondary circuit at the means for operating one of theA electrodes, levers,'and means for returning b'oth levers to normal position.

12. A' unitary piece of welding-'apparatus a transformer, primary piece of welding apparatus I contacts and a rheostat in the primary circuit of the transformer, welding electrodes connected to the secondary of the transformer, one of said electrodes being movable, vand one insulated from the other, a pair of levers, one actuated by movement of the other, means for moving the last mentioned lever to first move said movable electrode to engage the work with the other electrode, and then to lmove the first mentioned lever to close said switch contacts, said levers acting on their return movement, the one to open the switch contact in the primary circuit, and the other to open the said electrodes, and means for insuring that both levers are returned to normal position on release of the second mentioned lever.

13. A unitary vpiece of welding apparatus including; a frame, a transformer, switch contacts and a rheostat in the primary circuit of the transformer, and a pair of welding electrode arms carrying electrodes all supported by the frame, one of said arms'beking, movable and one insulated from the other, a lever having a spring take-up con* nection with said movable electrode arml` a second lever for operating said switch contacts, means co-acting between said levers to move the `second lever from the first, said spring take-up connection allowing the first lever to continue its' movement after closure ofthe welding electrodes on the work, and to move the second lever, the tension of said spring being adjustable to regulate the pres-A sure applied to the work by said electrodes, said co-acting means permitting the second lever to return to normal position before the first lever,v as and for the purposes described.

In testimony whereof, I affix my signature.

THOMAS M. HUNTER.

on to the work I including; a frame, a transformer, switch l 

